Inline intrusion detection

1. A method comprising:

in response to receiving a packet at a network gateway, assigning an identifier to the packet;

generating, by the network gateway, a copy of the packet;

inserting, by the network gateway, the identifier into a header of the copy of the packet;

storing the packet and the identifier identifying the copy of the packet at the network gateway;

transmitting the copy of the packet having the identifier in the header from the network gateway to an intrusion detection system;

maintaining the packet at the network gateway while the copy is analyzed by the intrusion detection system to determine whether the packet includes an attack signature;

receiving a reply message from the intrusion detection system at the network gateway, the reply message comprising the identifier extracted from the header of the copy of the packet and indicating one or more results of the analysis, the reply message further comprising a code representative of an action to take in response to the reply message, the size of the reply message less than the size of the packet; and

taking, by the network gateway, the action associated with the code in response to the reply message.

2. The method of claim 1 , the taking the action in response to the reply message further comprising performing an action selected from the following:

dropping the packet;

dropping the packet and dropping one or more related packets;

allowing the packet to pass from the network gateway to a protected network;

allowing the packet and one or more related packets to pass from the network gateway to a protected network; or

modifying the packet and then allowing the packet to pass from the network gateway to a protected network.

3. The method of claim 1 , wherein the reply message comprises an indication of whether the packet comprises an attack signature.

4. The method of claim 1 , wherein the action represented by the code is selected from the following:

dropping the packet;

dropping the packet and dropping one or more related packets;

allowing the packet to pass from the network gateway to a protected network;

allowing the packet and one or more related packets to pass from the network gateway to a protected network; or

modifying the packet and then allowing the packet to pass from the network gateway to a protected network.

5. The method of claim 1 , further comprising:

removing material indicative of an attack signature prior to allowing the packet to pass from the network gateway to a protected network.

6. The method of claim 1 , wherein taking the action in response to the reply message comprises:

determining that one or more additional packets received at the network gateway are related to the packet; and

disposing of the one or more additional packets, by the network gateway, in a same manner as the packet, wherein the one or more additional packets are not analyzed by the intrusion detection system.

7. A method comprising:

in response to receiving a packet at a network gateway, assigning an identifier to the packet;

generating, by the network gateway, a copy of the packet;

inserting, by the network gateway, the identifier into a header of the copy of the packet;

storing the packet and the identifier identifying the copy of the packet at the network gateway;

transmitting the copy of the packet having the identifier in the header from the network gateway to an intrusion detection system;

setting a timer upon transmission of the packet from the network gateway to the intrusion detection system;

maintaining the packet at the network gateway while the copy is analyzed by the intrusion detection system to determine whether the packet includes an attack signature; and

taking, by the network gateway, a default action in response to determining that the timer expired before a reply message is received from the intrusion detection system, the default action selected from the group consisting of:

allowing, by the network gateway, the packet to pass from the network gateway to a protected network; and

dropping, by the network gateway, the packet.

8. An apparatus comprising:

a memory configured to store a packet and an identifier identifying the packet at a network gateway; and

one or more processors configured to:

in response to receiving the packet at the network gateway, assigning an identifier to the packet;

generate a copy of the packet;

insert the identifier into a header of the copy of the packet;

transmit the copy of the packet having the identifier in the header from the network gateway to an intrusion detection system;

maintain the packet at the network gateway while the copy is analyzed by the intrusion detection system to determine whether the packet includes an attack signature;

receive a reply message from the intrusion detection system at the network gateway, the reply message comprising the identifier extracted from the header of the copy of the packet and indicating one or more results of the analysis, the reply message further comprising a code representative of an action to take in response to the reply message, the size of the reply message less than the size of the packet; and

take the action associated with the code in response to the reply message.

9. The apparatus of claim 8 , the taking the action in response to the reply message further comprising performing an action selected from the following:

dropping the packet;

dropping the packet and dropping one or more related packets;

allowing the packet to pass from the network gateway to a protected network;

allowing the packet and one or more related packets to pass from the network gateway to a protected network; or

modifying the packet and then allowing the packet to pass from the network gateway to a protected network.

10. The apparatus of claim 8 , wherein the reply message comprises an indication of whether the packet comprises an attack signature.

11. The apparatus of claim 8 , the action represented by the code is selected from the following:

dropping the packet;

dropping the packet and dropping one or more related packets;

allowing the packet to pass from the network gateway to a protected network;

allowing the packet and one or more related packets to pass from the network gateway to a protected network; or

modifying the packet and then allowing the packet to pass from the network gateway to a protected network.

12. The apparatus of claim 8 , the one or more processors further operable to:

remove material indicative of an attack signature prior to allowing the packet to pass from the network gateway to a protected network.

13. The apparatus of claim 8 , wherein, when taking the action in response to the reply message, the processor is configured to:

determine that one or more additional packets received at the network gateway are related to the packet; and

dispose of the one or more additional packets, by the network gateway, in a same manner as the packet, wherein the one or more additional packets are not analyzed by the intrusion detection system.

14. An apparatus comprising:

a memory configured to store a packet and an identifier identifying the packet at a network gateway; and

one or more processors configured to:

in response to receiving a packet at the network gateway, assign an identifier to the packet;

generate a copy of the packet;

insert the identifier into a header of the copy of the packet;

transmit the copy of the packet having the identifier in the header from the network gateway to an intrusion detection system;

set a timer upon transmission of the packet from the network gateway to the intrusion detection system;

maintain the packet in the memory while the copy is analyzed by the intrusion detection system to determine whether the packet includes an attack signature; and

take a default action in response to determining that the timer expired before a reply message is received from the intrusion detection system, the default action selected from the group consisting of:

allowing, by the network gateway, the packet to pass from the network gateway to a protected network; and

dropping the packet.

15. Logic embodied on one or more non-transitory computer-readable media and when executed operable to:

in response to receiving a packet at a network gateway, assign an identifier to the packet;

generate, by the network gateway, a copy of the packet;

insert, by the network gateway, the identifier into a header of the copy of the packet;

store the packet and the identifier identifying the copy of the packet at the network gateway;

transmit the copy of the packet having the identifier in the header from the network gateway to an intrusion detection system;

maintain the packet at the network gateway while the copy is analyzed by the intrusion detection system to determine whether the packet includes an attack signature;

receive a reply message from the intrusion detection system at the network gateway, the reply message comprising the identifier extracted from the header of the copy of the packet and indicating one or more results of the analysis, the reply message further comprising a code representative of an action to take in response to the reply message, the size of the reply message less than the size of the packet; and

take the action associated with the code in response to the reply message.

16. The logic of claim 15 , the taking the action in response to the reply message further comprising performing an action selected from the following:

dropping the packet;

dropping the packet and dropping one or more related packets;

allowing the packet to pass from the network gateway to a protected network;

allowing the packet and one or more related packets to pass from the network gateway to a protected network; or

modifying the packet and then allowing the packet to pass from the network gateway to a protected network.

17. The logic of claim 15 , further operable to:

remove material indicative of an attack signature prior to allowing the packet to pass from the network gateway to a protected network.

18. The logic of claim 15 , wherein taking the action in response to the reply message comprises:

determining that one or more additional packets received at the network gateway are related to the packet; and

disposing of the one or more additional packets, by the network gateway, in a same manner as the packet, wherein the one or more additional packets are not analyzed by the intrusion detection system.

19. Logic embodied on one or more non-transitory computer-readable media and when executed operable to:

in response to receiving a packet at a network gateway, assign an identifier to the packet;

generate, by the network gateway, a copy of the packet;

insert, by the network gateway, the identifier into a header of the copy of the packet;

store the packet and the identifier identifying the copy of the packet at the network gateway;

transmit the copy of the packet having the identifier in the header from the network gateway to an intrusion detection system;

set a timer upon transmission of the packet from the network gateway to the intrusion detection system;

maintain the packet at the network gateway while the copy is analyzed by the intrusion detection system to determine whether the packet includes an attack signature; and

take, by the network gateway, a default action in response to determining that the timer expired before a reply message is received from the intrusion detection system, the default action selected from the group consisting of:

allowing, by the network gateway, the packet to pass from the network gateway to a protected network; and

dropping the packet.